Electrical regulating apparatus



May 7, 1946. w. c. SEALEY ELECTRICAL REGULATING APPARATUS Original FiledNov. 13, 1942 Patented May 7, 1946 ELECTRICAL REGULATING APPARATU SWilliam C. Sealey, Wauwatosa, Wia, asslgnor to Allis-ChalmersManufacturing Company, Milwaukee, Wis, a corporation of DelawareOriginal application November 13, 1942, Serial No. 465,425. Divided andthis application August 17, 1945," Serial No. 611,053

2 Claims.

This invention relates in general to electrical regulating apparatus andrelates particularly to apparatus such as may be utilized in anelectrical regulator in which the use of oil as an insulating andlubricating fluid is avoided. This application is a division of parentapplication Serial No. 465,425, filed November 13, 1942, for Electricalregulating apparatus. a

In prior art step type voltage regulating apparatus, oil has generallybeen used both as an insulating and as a lubricating fluid. An apparatusof this type is shown in United States Letters Patent No. 2,177,109, L.H. Hill, granted October 24, 1939, which utilizes oil for lubricatin theoperating mechanism of the tap changer, for lubricating and insulatingthe tap changing switch contacts and for insulating the windings oi thetransformer. The problem of making electrical regulating apparatus ofthe above type fire proof or noninfiammable therefore involves bothinsulating and lubricating problems.

Transformer windings have been made fire proof by the use of air as aninsulating medium or by the use of synthetic noninflammable liquids. Thenoninflammabie liquids suitable for such insulating purposes haveundesirable properties requiring special equipment for handling, arehazardous from the standpoint of injury to personnel and are relativelyexpensive. Although air insulation necessitates greater insulatingdistances than does oil insulation, it is a good insulator but a poorlubricant. Prior art air insulated contacts have been lubricated,however, such lubrication has been detrimental to the current carryingcapacity of the contacts. It is therefore an object of the presentinvention to provide an electrical regulating apparatus with switchcontacts which are airor other gas insulated but which are at the sametime lubricated. during relative motion thereof with a noninflammablelubricant.

It is a further object of the present invention to provide gasinsulated, frlctionally engaged switch contacts with a noninflammablelubricant which does not impair the current carrying characteristics ofthe contacts.

Objects and advantages other than those above set forth will be apparentfrom the following description when read in connection with theaccompanying drawing in which:

Fig. 1 is a diagrammatic showing of a voltage regulating system andapparatus embodying the present invention;

Fig. 2 is a detailed view of the dial switch contacts shown in Fig. 1;

Fig. 3 is a bottom detail view of the fixed contact shown in Fig. 2; and

Fig. 4 is an end-view of the contact structure shown in Fig. 2.

In Fig. 1, a tap changing switch 9 selectively connectsdiii'eringamountsof a winding 8 into a load circuit I to control the voltage thereof. Thewinding 8 is excited from an excitingwinding "I connected across thesupply circuit 6. The voltage of load circuit 5 is maintained constantby including more or less of the winding 8 therein in response to actionof a contact making voltmeter ll.

The operating apparatus for the tap changing switch 8 includes a'motor21 connected in driving relation to a shaft 36 by a geared shaft 22 andaiso'includes the shafts 28 and 32 driven from the shaft 22 to operatethe contactors i4 and I5, respectively. The sequenceof operations of theoperating mechanism is such that the load circuit is made and broken atthe contactors H and II, thus a change in the setting of the dial switch8 is made only when the pertinent contactor H or I! is in open position.The contacts l2 and I3 of the dial switch 9 therefore do not make andbreak any current, but function to carry the heavy load current throughselected portions of winding 8.

The operating mechanism may be insulated with a noninilammable gas andthe various bearings thereof may be lubricated with oilless bearings ofthe type using graphite or some similar lapping compound. The contactorsI 4 and I5 are air break switches of any type suitable for making andbreaking current in air.

The windings I and 8, which are on the same core, may be insulated by anoninfiammable liquid or may be insulated by a noninflammable gas suchas air. In the prior art structures, the dial switch 9 has been immersedin oil for insulation and for lubrication purposes. In order to make anoninfiammable regulating apparatus, in they present invention the dialswitch 9 is insulated by air or some similar insulating gas and islubricated in a fire proof manner that will not impair the currentcarrying function of the dial switch contacts. g

The dial switch 9 has fixed contact plates in circumferentially spacedfor selective connection of one or a pair thereof into the load circuitby means of a plurality of pairs of movable contacts l2 and i3.Considerable contact pressure is desirable between cooperating fixed andmovable contacts in order that the heavy load current may be safelycarried thereby without over heat- 44 are rigidly fastened to thecontacts l2 and I3 and slide in cooperating holes in the guides 43. Thecontact pressure against the faces of contact plate in is provided bysprings (not shown) between the guides 43 and the contacts l2 and i3.When the contacts I2 or l3 are not contacting a plate It, the pins 44hold the two parts of the contact slightly apart so that they can moreeasily slide over the beveled edge 40 of the next plate [0. The platesin are mounted on supporting members 42 and are held in positionby'machine screws 39.

When the pairs of contacts I: and 13 are in a tap connecting position,these contacts may be positioned as shown in Fig. 2, where both pairs ofcontacts cooperate with the same plate It, or they may be on adjacentplates III. In either case, the contacts I2 and II are on end,noncentral or main current carrying portions of a plate It when in tapconnecting position, and at least one of these contacts must sweepacross the central or lubricating portion of a plate l during selectivemovement in arriving at a tap connecting position.

In the prior art, a dial switch such as 3 was insulated by immersion inoil and, therefore, the problem of lubrication was simple. In thepresent invention lubrication between the contacts l2 and i3 and theplates I0 is provided by a lapping compound such as graphite. Thelubricant is positioned for effective action on both contact faces byinclusion in holes 33 drilled in the stationary contact l0.

As shown in Fig. 2 the graphite inserts are placed in the central orlubricating portion of the plate it, where the graphite inserts do notinterfere with the carrying of heavy currents by the dial switchcontacts when in a tap connecting position. However, by placing thegraphite inserts in the central portion of the contact plates [0, one orthe other of the contacts l2 or l3 will sweep across the graphite and belubricated upon movement from one tap position to the next. Use of thistype of lubrication permits air insulation to be used for the dialswitch 9.

If the voltage of the circuit 5 varies from normal the contact makingvoltmeter l1 responds to the increased or decreased pull of the coil i3to close contact IE or contact 20. The motor 21 is thereby energized ina proper direction and turns the shaft 22. A gear 23 on shaft 22 isprovided with three pins 25, 26 and 21 which coact with the gears 30 and33 to operate the switches l4 and I5.

In the position shown in Fig. 1 the gear 23 has been rotated in thecounterclockwise direction and the pin 25 has turned the gear 30one-third of a revolution thereby opening the switch l4. This movementof the switch i 4 was effected by turning of the shaft 23 and eccentric28. During this movement, a second gear 34 on the shaft 22 was rotatedin a counterclockwise direction to the position shown where pne of thepins 35 is meshed with the gear 31. Further counterclockwise rotation ofthe shaft 22 will move thedial switch in a clockwise direction so thatbrush I2 occupies the present position of brush l3 and brush i3 is movedto the next contact plate l0.

During this rotation of the shaft 22, the pin 26 and the gear 23 willhave moved the shaft 29 a third of a revolution thus placing the switchI4 in a position to be closed upon further rotation of the shaft 22. Theclosing of switch I4 is accomplished by the pin 21 giving the shaft 29 afinal one-third movement, closing the switch l4 after the contact l3 hasreached the end portion or noncentral portion of the next contact plateiii. If a further voltage change in'the same direction is initiated bythe contact making voltmeter H, a further clockwise rotation of the dialswitch is obtained with the switch l5 breaking the circuit to the brushi2 and making it after the brush [2 has reached the new contactposition. This is accomplished by action of the pins 25, 26 and 21 onthe gear 33 to actuate the switch by means of the shaft 32 and theeccentric 3i. One-half of the auto-transformer I 6 takes the loadcurrent when the switch I4 or I5 is open.

The motor is shown as being energized from the load circuit 5, however,it may be energized from a winding on the same core as the windings 1and 8. The switches i and I5 are connected in circuit, respectively,with the brushes l2 and I3 through the collector rings II, the brush i2being insulated from the ring contacting the brush l3 by an insulatingmember 45.

Although but one embodiment of the present invention has beenillustrated and described it will be apparent to those skilled in theart that various changes and modifications may be made therein withoutdeparting from the spirit of the invention or from the scope of theappended claims.

It is claimed and desired to secure by Letters Patent:

1. In a plural circuit switch, a fixed contact provided with contactfaces on opposite sides thereof, said contact provided with a pluralityof main current carrying portions, a lubricating portion positionedbetween said main current carrying portions, inserts of solidlubricating material in said lubricating portion only and extendingthrough said contact from one of said contact faces to the other of saidcontact faces, and a plurality of pairs of movable contacts arranged tocooperate in rubbing engagement with opposite faces of said main currentcarrying portions to normally close a heavy current load circuit andarranged to cooperate in rubbing engagement with opposite faces of saidlubricating portion only during movement of said movable contacts.

2. A switch comprising a fixed contact provided with a plurality of maincurrent carrying portions, a lubricating portion positioned between saidmain current carrying portions, a movable contact, means for moving saidmovable contact in rubbing engagement with said lubricating portion onlyduring movement of said movable contact from one to another of said maincurrent carrying portions, and inserts of solid lubricating material insaid lubricating portion and extending to the surface thereof engaged bysaid movable contact.

WILLIAM C. SEALEY.

